/*
 * Copyright 2011-2025 GatlingCorp (https://gatling.io)
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package io.gatling.core.action

import scala.collection.mutable

import io.gatling.commons.util.Clock
import io.gatling.core.actor.{ Actor, ActorRef, ActorSystem, Behavior }
import io.gatling.core.session.Session
import io.gatling.core.stats.StatsEngine
import io.gatling.core.util.NameGen

private object RendezVous extends NameGen {
  def apply(users: Int, actorSystem: ActorSystem, next: Action): RendezVous = {
    val actor = actorSystem.actorOf(new RendezVousActor(users, next, genName("rendezVous")))
    new RendezVous(actor)
  }
}

private final class RendezVous private (actor: ActorRef[Session]) extends ActorDelegatingAction(actor.name, actor)

/**
 * Buffer Sessions until users is reached, then unleash buffer and become passthrough.
 */
private final class RendezVousActor(users: Int, val next: Action, name: String) extends Actor[Session](name) {
  private val buffer = mutable.Queue.empty[Session]

  override def init(): Behavior[Session] = session => {
    buffer += session
    if (buffer.sizeIs == users) {
      buffer.foreach(next ! _)
      buffer.clear()
      become(passThrough)
    } else {
      stay
    }
  }

  private val passThrough: Behavior[Session] = session => {
    next ! session
    stay
  }
}
